1. Field of the Invention
The present invention relates to a circuit pattern formation device for forming a circuit pattern on a printed circuit board or the like, and a method of forming the circuit pattern.
2. Background of the Invention
Attention has been given to a system for forming a circuit pattern on a substrate by a printing process consisting of simple steps such as a screen printing process, a dispenser process, an inkjet printing process and an electrophotography printing process, as a substitutional technology for a conventional photolithographic system which needs an expensive mask and multistage process. Any of the processes forms a pattern by using a conductive particle dispersed solution containing electroconductive particles dispersed in a solvent, or a toner containing electroconductive particles added into a resin, and by applying the dispersion or the toner indirectly with a printing plate or a screen, directly with a nozzle scanning technique, or with an electrostatic adsorption technique. And the wirings are formed by heating the substrate to bake the pattern and by causing fusion-bond of the particles to form a conductor.
Among the various printing processes described above, the electrophotographic system of forming a desired circuit pattern on an insulation substrate with the use of an electrostatic force has many advantages in comparison with the other processes, because the system can be used for not only mass production and large-area pattern formation but also change of the circuit pattern which is advantageous for high-mix low-volume production. Among the electrophotographic systems, in particular, a liquid development system of using a conductive particle dispersed solution containing electroconductive particles dispersed in a solvent as a developer is advantageous in that the liquid development system can enhance a resolution of the pattern and lower a baking temperature at which the electroconductive particles are fused into a conductor, because the system can prevent particles from scattering by dispersing them in a liquid and can use conductive particles with a smaller grain size.
In a pattern formation device with the use of the liquid development system the surface of a photoreceptor is uniformly electrified and a desired electrostatic latent image is formed using a laser scan exposure system. And then, the electrostatic latent image is contacted with a liquid developer and particles of a pattern formation material dispersed in the liquid are electrostatically adsorbed onto the electrostatic latent image through electrophoresis to develop the pattern, and the obtained developed pattern is directly or indirectly transferred onto an objective substrate.
The means for transferring the developed pattern in the above described process includes a method of transferring the developed pattern by applying heat or pressure on the pattern; and a method of transferring the developed pattern through an electrostatic force by applying an electric field to the particles (see e.g. JP-A-2002-91171).